Morphology and Dynamics of Gas-dust Jets in Comet 67p/Churyumov-Gerasimenko from Ground-based Ccd Observations

Ground-based CCD observations of comet 67P/Churyumov-Gerasimenko were carried out during October 5-8, 2021 at the Sanglokh International Astronomical Observatory using the Zeiss-1000 reflector telescope equipped with an FLI ProLine 16803 CCD camera and broadband BVRI filters. The morphology and dynamics of gas-dust activity in the near-nucleus region were investigated using image-enhancement and photometric processing techniques. Application of the Larson-Sekanina rotational gradient filter revealed several asymmetric gas-dust jet structures whose morphology and orientation changed during the observing interval. Projected jet lengths, position angles, and particle ejection velocities were estimated from the processed CCD images. Dust-particle velocities were calculated using the Whipple and Jones dynamical models. The obtained results show that particle ejection velocities strongly depend on particle size and thermal conditions near the nucleus surface. According to the Whipple model, the derived velocities vary from approximately 35 m/s to 417 m/s, while the Jones model yielded lower characteristic velocities for larger particles. Thermal characteristics of several volatile species, including H 2 O, CO, O 2 , and CO 2 , were additionally investigated using simplified sublimation relations. Isophotal analysis revealed a pronounced asymmetry of the inner coma and confirmed the presence of anisotropic dust emission associated with localized active regions on the nucleus surface. Temporal variations in jet orientation allowed the rotational period of the nucleus to be estimated within the interval 11.5-12.5 h, which is consistent with previous Rosetta mission measurements. The obtained results demonstrate that medium-aperture ground-based telescopes combined with modern CCD image-processing techniques remain effective tools for investigating cometary activity and dust dynamics. The study also confirms that ground-based observations are capable of reproducing large-scale morphological features previously detected during spacecraft investigations of comet 67P/Churyumov-Gerasimenko.